How to Rename Certain Observations in Column Based on Certain String Value?

Question

I'm looking to rename certain values of my column based upon a certain string. My current data resembles this example:

PlayerID

Hank_Aaron+7
Babe Ruth+5
MMM + 7
Willie Mayes+1
MMM + 3

I would like to rename all observations that start with "MMM" to be just "MMM". For example, I want the above table to ultimately look like this:

PlayerID

Hank_Aaron+7
Babe Ruth+5
MMM
Willie Mayes+1
MMM

I also need to keep the column in the same dataframe so that I can use it for regressions. Thank you in advance!

akrun · Accepted Answer · 2020-07-13 22:05:55Z

2

With grep, find the position index of 'MMM' string, extract those, then do an assignment (assuming 'PlayerID' is character class and not factor class)

df1$PlayerID[grep("^MMM", df1$PlayerID)] <- "MMM"

answered Jul 13, 2020 at 22:05

akrun

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1 Comment

887 Over a year ago

Wow, that seems to have done it. Thank you so much!

Ronak Shah · Accepted Answer · 2020-07-14 00:31:23Z

0

We can use startsWith :

df$PlayerID[startsWith(df$PlayerID, 'MMM')] <- 'MMM'

We can also use this in replace :

df$PlayerID <- replace(df$PlayerID, startsWith(df$PlayerID, 'MMM'), 'MMM')
df
#        PlayerID
#1   Hank_Aaron+7
#2    Babe Ruth+5
#3            MMM
#4 Willie Mayes+1
#5            MMM

data

df <- structure(list(PlayerID = c("Hank_Aaron+7", "Babe Ruth+5", "MMM + 7", 
"Willie Mayes+1", "MMM + 3")), class = "data.frame", row.names = c(NA, -5L))

answered Jul 14, 2020 at 0:31

Ronak Shah

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2 Comments

887 Over a year ago

Thank you for your response Ronak! Is it possible to do this in the opposite direction? For example, what if I wanted to re-name the Player-ID column according to the number at the very end of PlayerID? As such: ``` PlayerID NewID Hank Aaron + 7 7 Babe Ruth + 5 5 Ted Williams + 2 2 Hank Aaron + 5 5 ``` Is there maybe an endswith command? Also if you believe this question merits a new post please let me know.

Ronak Shah Over a year ago

There is endsWith as well but it needs a fix suffix like "5", or "6" etc, writing this for all combinations can be tiring. So you can use grepl here to match with any digit df$PlayerID[grepl('\\d$', df$PlayerID)] <- 'MMM'

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